Re: Swap out Glock guide rod assembly?
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Shorter, understanding the remarkable difference between product improvement vs correcting product failure.
For the unwashed:
Gen II
Checkering front strap and serrations to the back strap
GEN III
accessory rail, thumb rests on both sides, finger grooves on the front strap. Later, modified extractor that also serves as a loaded chamber indicator, cross pin. Black or olive drab and, yes, a dummy gun.
GEN IV
ergonomics, recoil spring assembly, rough texture frame, grip checkering, and interchangeable backstraps. Mechanically, dual recoil spring, slide and barrel shelf have been resized due to the larger diameter of this dual recoil spring assembly. The front portion of the polymer frame under the slide also has been widened and internally enlarged in order to accommodate the dual recoil spring assembly.
Next.